Teletypewriter



Sept. 29, 1953 A. A. SWEENY ET AL TELETYPEWRITER Filed Sept. 27, 1951RECEIVER 5 INVENTORS ALFREDAJ'WfENY MAURICE F. .rweeuy STAT/0N AZita/ways Patented Sept. 29, 1953 TEEE'IYPEWRITEE Alfred A. Sweeny,-Denver, and Maurice F. Sweeny, Silt". Colo.

Application September 27, 19.51,.S.erial-No.'248,57l6

1 Claim. 1

This invention relatestov improvements in teletypewriters and hasreference more particularly to a wireless teletypewriter mechanism.

Telety-pewriter machinesv of various kinds are now. inuse for sendingand distributing information such asnews, stock reports and/or messagesof various kinds. Such machines, being mechanical and operated byelectromagnetic devices, including relays, magnets and. escapements ofvarious. kinds, are highly complicated, very costly and-subject tobreakdowns.

It is. the object of thisinvention to produce a mechanism that willtransmit messages. from one place to another either overmetalliccircuits or. by means. of modulated radio carrier waves, and whichshall. have a minimum of parts.

Another object is toproduce amechanism of such construction that themessage; can be sent by manually operated or perforated paper tapeoperated keys corresponding to the ordinary typewriter keys and whichwill receive the message at a distant station. and. print it. ona tapein easily readable form.

Ihe above andany other objects that may become apparent as thedescription proceeds are attained by means of'a construction and anarrangement of parts that will now be described, for which purposereforencewill behad' to the'accompanying drawings in which the inventionhas been illustrated and in which the. single figure is a diagramshowing the several elements. in their operative relation showing amanual keyboard control;

In the drawings, reference character M designates a synchronous motor,preferably a two pole motor, and S designates ashait directly con.-nected' with the motor. Secured to the shaitiis 'a slip ring IS" withwhich brush llj cooperates.

The shaft carries a number of disks [2 'of'inr sulating material; thereis a separate disk. for each letter, number and/or other character. tobe transmitted, whichpreferably corresponds to the characters on astandard. typewriter. Each disk has a short metal segment. [3, in its.periphery and these are all connected'witha common conductor I I bymeans of. radial. conductors l5.. A brush [6 is positioned to contactwith the periphery of each disk. Brushes. ware all post.- tioned in thesame radial plane passing through the shaft axis, as. shown. A, disk.G,. somewhat larger in diameter than disks. L2, is attached to the endof the shaft opposite. from. the motor. If disk G is made. from opaquematerial, it: has all of the letters numbers and. other characters asindicated at Ll. Disk G may, however,v be made. from/transparent plasticor other suitable transparent material and. covered. with. an. opaquepainter other opaque outer film whichmay have Darts removed to form;the-letters. A str0botron" lamp I8 is positioned, preferably, but. notnecessarily, in. the radial plane thatcontains brushes t6, and isvprovided on one side with a transparent window through which abeam oflight emerges whenever the lamp functions, which beam is adjusted totravel in the radial plane above referred to and tov strike disk (3 in aposition to project light through. the stencils or through thetransparent areas outliningthe letters and/or othersymbols. A lens l9may be interposed between thelampand disk G tocollimate the rays fromthe lamp. Positioned on the far side. of disk G. is, a sensitized tape20thatis moved, from right to left by means 015a step by step mechanismcomprising. a ratchet wheel '21 and a pawl 22*operated: by solenoid. 23when it is energized bya. current. from the: multivibrator triggercircuit 24..

Messages. areinitiated, by means of an. apparatus that will now bedescribed.

Asourceot direct. current, for example a storage battery BAT, oi thedesired voltage and capacity is provided and has one pole grounded at E.A conductor 25 is; connected withthe other pole and extends to akeyboard where it forms the commonlead for all of the sending keyswitches which. will now be described. The sending apparatu has akeyboard similar to that of a typewriter, having one key for eachletter, number,.punctuatiommark; and any specialcharactor that. may bedesire d;. thereis only one key for each letter, as capital letters onlyare used. In the drawing. only three keys are shown, one representing,the. letters, one representing the numbers andtheother the punctuationmarks and. special characters, if any. Associated with each keyisastationary 'switchcontact 21.. For the-purposeof this explanation,the stems ZtA of the-keys will be considered-as made from insulatingmaterial. Springs." areassociated with the keys andsnormally hold themin the. elevated position shown in: the drawing. Attached. toeach keystem are switch contacts 29 and 29A that are. moved into engagement.with. the correspondingstationary contacts; Z1; whenever the keys aredepressed. Numeral all-designates.- a spacer bar that isheld-in elevatedposition by springs 3i and which has insulating stems, 32. that carryswitch contacts 33 and 33A into. engagement with. concut, therein: asstencils. and arrangedtin. a circle 55. tacts u when the bats are.-depressed.

Conductors 35 connect the movable contacts 29 with the correspondingbrushes I6. The one that is connected with the movable contact 29 of theA key extends to brush I6 at the disk nearest disk G and the othersfollow in regular order.

Station A is provided with a relay comprising solenoid coils 35A and 36.A magnetic core 31 is operatively associated with the solenoids and isconnected with two spaced movable spring type relay contacts 43 and 39.Contacts 39 and 49 are normall in engagement. When the solenoid isenergized, core 31 will be moved towards the left, thereby openingcircuit at 39, 40 and closing contacts at 38, 43.

Let us now assume that key A is depressed. Contacts 29 and 29A will thenbe moved into engagement with contact 21 and the corresponding conductor35 will be energized. When contact I3 on the first disk I engages brushI6, current will flow through conductor I4 to slip ring I0, thencethrough wire 42 and through contact 40 and 39 to multivibrator 24 and tothe pulse shaping circuit. Multivibrator 24 operates solenoid 35A whichattracts core 31, moving switch members 33 and 39 to the left whereuponcircuit 38, 43 will close and 39, 40 open. When key A is moveddownwardly, contact 29A also becomes energized by engagement withcontact 21, thereby energizing conductors 44, whereupon current flowsfrom 44 to 38, thence through the solenoid 35 to ground, locking therelay.

Attention is called to the fact that the current in wire 42 has acomplete conductive path to the pulse shaping circuit after it passesrelay contacts 39, 40 and is not delayed by reason of the impedance ofcoil 35A and the inertia of the armature 31.

The pulse of current which reaches the pulse shaping circuit is modifiedand passed on to the modulator and radio transmitter. When key A isreleased, wires 35, 44 are de-energized and the solenoid relay isthereby unlocked, and the parts return to the position shown on thedrawing. When another ke is depressed the operation just described isrepeated.

When words are to be spaced, bar 30 is moved downwardly, whereuponcontacts 33 and 33A engage the live contact 34 in the same manner asexplained in connection with contacts 29 and 29A.

The apparatus just described has been designated as Station A. Identicalapparatus is located at Station B, and at all other stations if morethan two are used.

On the drawing, a few of the elements of Station B have been indicated.The radio receiver is connected by wires to the trigger circuit I24 andconductors project from the trigger circuit, which have been designatedby numeral 48.

It must be remembered that the equipments at the two stations areidentical. In Station B, the motor has been designated by MB todistinguish'it from motor M at Station A. The two synchronous motors Mand MB are connected for synchronous operation by any one of the severalmethods commonly employed for this purpose, and the shafts S at the twostations therefore rotate in exact synchronism.

Whenever the pulse shaping circuit is energized, which occurs each timea sending ke is pressed down, a pulse is instantly transmitted to themodulator which modulates, keys or interrupts the carrier wave sent outby the radio transmitter. The carrier wave is received at Station B, andthe modulations, or interruptions or pulses operate trigger circuit I24all of which is common in the art of radio. Trigger circuit I24 throughconductors 49 cause the strobotron to light. Since such impulses arecontrolled as to time by the closing of circuit from any one of brushesI6 to the corresponding contact I3, and since the brushes are all in theradial plane which also contains the strobotron, such impulses will takeplace and the strobotron glow at the instant that the correspondingletter, figure or other symbol on disk G is in line with the light beamfrom the strobotron; light will therefore pass through the stencilopenings of the corresponding letter or figure, etc., and strike thesensitized paper 20 which is positioned in a light-proof compartment.

Brushes I6 and conductors I3 are of a width to allow for engagementthrough the maximum angle of hunting of the motors.

The strobotron is connected through conductor 58, brush 51, commutator56, conductor 55, slip ring 54, brush 53, conductor 52, rheostat SI, andconductor 50 to the battery. Battery potential on the strobotron isnecessary before it can be fired by the signal from the receiver. Due tothe very narrow brush 5! and the size and arrangement of the conductorsof commutator 56, the strobotron fires at only the instant when a letteron disk G is at exactly its maximum height of travel, thus reducingdistortion.

At the time the strobotron is lighted, solenoid 23 is energized andmoves the sensitized tape one space. The tape moves in the samedirection as the upper part of disk G, and therefore any distortion dueto relative movement is prevented. Since the times here dealt with areexceedingly small, practically no distortion results, even when the tapeis stationary at the time the light strikes. The exposed tape isdeveloped by contact with gas in a well known manner, and the charactersbecome visible and readable. A separate symbol, as for example, an opensquare or oblong figure, may be used to indicate a space between words,and it is possible to leave such spaces blank as on an ordinaryteletypewriter tape.

Operation When a message is to be transmitted from Station A to StationB, it is spelled out by striking the keys in the same manner as on atypewriter or teletypewriter machine. The two motors M and MB areoperated in synchronism as above explained. If key A, for example, isstruck, conductor 35 will be connected with the ungrounded pole of thebattery, and when contact I3 engages the brush I 6 on the A disk I 2,relay coil 35 is energized and by means of radio as described above, thetrigger circuit and strobotron is activated. Since the source of light,brushes I6 and the stenciled character corresponding to any disk I2 areas previously pointed out, in the same diametrical plane, the image ofthe character will be projected onto the tape at the same point relativeto the two axes of the tape rolls. After or during each exposure,solenoid 23 functions to step the tape ahead one space. Any lag due tothe small time constant of solenoid 3G and associated parts can becompensated for by a corresponding angular adjustment of disk G relativeto disks I2.

Disk G and tape 20 are preferably enclosed in a light-tight compartment,a portion only of which has been indicated by broken lines, or allequipment at each station with the exception of the keyboard may beenclosed in a light-tight compartment. The tape may be of the type thatis developed by contact with a gas, sometimes referred to as Ozaprints.There are several methods being practiced which may be employed fordeveloping the tape, and this has therefore not been shown.

Attention is called to the fact that the circuit illustrated on thedrawing is of the block type in which the strobotron, the modulator andthe trigger circuit have been identified by name. These elements arewell known to and understood by persons versed in this art. In the bookentitled Basic Radio by Hoag, Van Nostrand Co., Inc, tenth printing, inchapter 19, on page 127 the circuit contemplated for the trigger circuitis shown. Either the simple counting circuit (Figure 19A) or the selfstopping circuit (Figure 193) may be used, the latter being preferred.In chapter 18 beginning on page 120 the circuit and elements indicatedon the drawing by the word strobotron are shown and explained (Figure18D), and in chapter '16 the various embodiments of modulators areshown. The trigger circuit may be a one shot multivibrator as is definedin Principles of Radar, M. I. T. School motors may be synchronized inany of the several Ways now employed for this purpose.

In Figure 1 of the drawing and in the specification, a strobotron and asensitized tape have been shown and described as the means for recordingthe message, as this may be efiected by simple mechanical means.

Having described the claimed as new is:

A device for transmitting intelligence to and from two spaced stationscomprising, in combination, a set of movable keys, one for eachcharacter to be transmitted, a source of direct electric current onepole of which is grounded, a stationary contact electrically connectedwith the ungrounded pole of the current source, operatively positionedadjacent each key, each key having two electrically insulated contactspositioned thereon for movement into electrical engagement with thecorresponding stationary contact, each device having a rotatably mountedshaft, means comprising a synchronous motor invention, what is connectedwith said shaft to effect synchronous rotation of the shafts of spaceddevices, each shaft having a disk attached to one end thereof, said diskhaving the characters to be transmitted arranged in a circular zone, inangularly spaced relation, the characters having transparent outlines,the shaft having a contact for each character supported thereon forconjoint rotation therewith, each contact moving in a circular path whenthe shaft turns, a brush positioned in the path of each contact so as tobe in conductive engagement therewith once each revolution of the shaft,the several contacts being angularly spaced so that they come intoengagement with their corresponding brushes successively when the shaftturns, the angular displacement of the contacts being equal to 360degrees divided by the number of characters, a strobotron positioned tothrow a beam of light on the zone of the disk which contains theoutlines of the characters, a slip ring on the shaft, means forelectrically connecting all of the said contacts with the slip ring, oneof the two contacts on each key being electrically connected with one ofsaid brushes whereby the said contact on the key will be in electricconductive relation with the slip ring once each revolution of theshaft, means effecting an operation of the strobotron at the instantwhen an energized brush comes into electric engagement with a rotatingcontact whereby the character on the rotating disk which corresponds tothe energized brush will be illuminated, means including a multivibratorand a pulse shaping circuit connected in parallel to the slip ring, alocking relay operatively connected with the multivibrator for breakingthe circuit from the slip ring to the multivibrator and the pulseshaping circuit after the multivibrator has functioned to allow only asingle operation of the strobotron for each operation of a sending key,and means comprising a photosensitive tape for producing a photographicrecord of the characters successively illuminated by the strobotron.

ALFRED A. SWEENY. MAURICE F. SWEENY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,074,037 Watson Mar. 16, 1937 2,104,543 Lemmon Jan. 4, 19382,104,544 Lemmon et al Jan. 4, 1938 2,407,336 Young Sept. 10, 19462,510,072 Clark June 6, 1950 2,578,025 Sweeny et a1. Dec. 1'1, 1951

